Stroker Crank Question

If you put a stroker crank in a regular engine can you use existing rods and heads? Would things bang into each other?

As long as you use a piston with a shorter "pin height" to match the increased stroke of the crank you should be ok. But many stroker cranks use the Chevy rod journal size so you'd have to find a crank that uses stock Mopar journals - probably not that big of a deal. Keep in mind that all things being equal, an increase in stroke increases compression ratio, so you'd have to take that into account when buying the pistons.

Mopar used long rods compare to other brands so there is lots of possibilities with a 440 or hemi length rod in a stroker. 383,400 rod are too short for most stroker builds, the bottom of the piston hits the crank counterbalances...but there are applications using them yet.
It's not hard to use a little math and figure out what fits in a stroker: first you need the deck height of your engine:
Rb is 10.725 approximately
B. Is 9.98 approximately
Subtract half your crankshaft stroke
Subtract your length of your connecting rods.
What is left is your piston compression height needed to achieve zero deck.

We have a 4.25 stroke with stock 440 rods rb with iron heads in the our 69 charger been running since 1994.. Imo when you use aftermarket heads on a stroker you will be beyond the hp limitations of a stock rod even with good bolts....If you drive it hard like I do.

SteveSS said:

If you put a stroker crank in a regular engine can you use existing rods and heads? Would things bang into each other?

Click to expand...

As mentioned, with the correct pistons, and the correct size rod journal size (diameter and width) on the crank it can be done. Because the aftermarket cranks have radius journals, you would need narrower bearings and you might also have to chamfer the rods to clear the radius of the crank. You would also have to balance everything.
Off the shelf pistons for a stroker with the stock pin size seems smaller than the selection with the GM 0.990" pin size used on most of the aftermarket rods.
Many stroker kits use the aftermarket connecting rods that have the GM 2.20" rod journal size, and bushed 0.990" pin size, along with the larger 7/16" cap screws holding the rod ends on, so for not too much more than stock rods, you get a rod that is alot stronger and setup for full floating pin. The 2.20" rod bearing allows more clearance between the rod and engine block, and the smaller pin allows a higher pin height in the piston whuch allows either more stroke or longer rod lengths.

When you take into account that you'll be buying a crank and pistons, a few extra bucks for new rods is nothing. And then you wouldn't have the concerns of finding a crank with the right size journals to fit the stock rods or pistons with the stock size pins. In fact you'd be wise to just buy a kit from someone like 440Source and get everything in one package.

Mostly repeating what has been said.... using a chevy aftermarket rod is common nowadays, and they are typically more affordable in the aftermarket for a BBC vs mopar. The best part is you don't have to grind as much on the block and are closer to just dropping in. The stock 440 rods have studs/nuts that stick out farther then the aftermarket 7/16 bolts. You combine that with the smaller 2.2 BBC vs 2.375 mopar rod journals= far less grinding for clearance...saves time. And you can put in a bigger throw without worrying about grinding into a water jacket. Most but not all of the mopar journal sized stroker cranks come from the hemi racing applications. But beware of billet hemi cranks, they are good for ridiculous hp, but you have to machine a place to center torque converter, the key way is larger for the dampener/supercharger and they require extra oiling because the rods journals are cross drilled. Extra time and machining required.

The difference in rod bolt size makes a large difference in strength. The area of a 7/16" bolt compared to a 3/8" is 26.53% larger.
The area of 3/8" = 0.110447, and 7/16" = 0.15033.
If using a 8740, 180,000 PSI bolt, the tensile strengths are 3/8" = 19,880 lbs, the 7/16" = 27,059 lbs
Also, don't confuse PSI with 1" diameter which only has an area of 0.785398 , or using the 180,000 PSI, the 1" diameter bolt strength is 141,371 lbs

Since each cap has two screws/bolts, the combination of 7/16" bolts is 53% stronger than the 3/8" bolts just because of the size difference.

So if using 3/8" bolts, and the ARP 2000 material rated at 220,000 psi the 3/8" bolt strength would come closer at 24,298 lbs
and using L19 or the other 260,000 psi materials, you could slightly exceed the 7/16" 8740 material strength with the 3/8" being 28,716 lbs